Very good trick
What really defines apocalyptic belief is not the idea that the world will at some time end, but that such and end is eminent and will soon be experienced. Yet what value is there to belief in an eminent end? Without having something "on the line", as the premise of this thread suggests", belief that the world as we know it is soon to expire means very little. As open mind poitns out, even JWs that argue "we have no date" actually do have relative dates fixed in their minds.
An interesting aspect to this involves the pracitice on individual members setting relative dates. Everybody in the group is encouraged to believe that the end is extrondinarly close, but must "make up the difference" in their own minds by creating boundries. I remember one JW even joking about this, saying that no matter what year it was we were always 12 years away from armageddeon.
Of course, the real goal for the preaching of eminence is rooted in the desire to change peoples behavior. The WTS is rather open about this, believing that they are saving lives.